java - 每当我调用Activity时，应用程序崩溃并给出错误

public class MainActivity extends AppCompatActivity {

FirebaseDatabase firebaseDatabase = FirebaseDatabase.getInstance ();
DatabaseReference databaseReference = firebaseDatabase.getReference ();
ListView listView;
List<String> ListString = new ArrayList<String> ();
@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate (savedInstanceState);
    setContentView (R.layout.activity_main22);
    ListString.add ("Hello");
    databaseReference.addValueEventListener (new ValueEventListener () {
        @Override
        public void onDataChange(DataSnapshot dataSnapshot) {
            DataSnapshot snapshot = dataSnapshot.child ("User");
            for(DataSnapshot s: snapshot.getChildren ())
                Toast.makeText (MainActivity.this, s.getKey ().toString (), Toast.LENGTH_SHORT).show ();

        }

        @Override
        public void onCancelled(DatabaseError databaseError) {

        }
    });

    listView = (ListView) findViewById (R.id.listview);
    ListAdapter listAdapter = new ListAdapter (MainActivity.this, ListString);
    listView.setAdapter (listAdapter);
    DatabaseReference s = databaseReference.child ("User");
    DatabaseReference p = s.child ("Name");
    p.setValue (ListString.get (1));

} }

正如我所说的，每当我调用此 Activity 时，它就会使应用程序崩溃，并且logcat是

最佳答案

这行导致错误

p.setValue (ListString.get (1));

您在ListString中只有一个值，并且访问第二个值，将其更改为以下值

p.setValue (ListString.get (0));